Eating things will give you extra abilities for a limited time. You have to be standing right ontop of something to eat it. You can eat everything.

To pick up a weapon, like a lead pipe, cricket bat or delicious pie, stand on it and press A.

DESCRIPTION:

It's a side-scrolling brawler that combines Streets of Rage with Kirby. Set in an anonymous bumtown ghetto, you'll have to chomp your way through 8 levels and 6 bosses, with 10 achievements to unlock.
Eat things to transform: Eat trash cans, hedges, basketballs, bicycles, post boxes, dogs, treadmills, cash tils and delicious pies. Can you eat enemies? I don't know, maybe if you could get them to stop punching you.